Filling an annular space between radially spaced coaxial tubes with foamed cement

ABSTRACT

A method and an apparatus are disclosed for filling the annular space between radially spaced coaxial tubes constituting a double walled pipe. The pipe may be of extruded plastic and comprised inner and outer coaxial tubes with bracing and spacing means therebetween. The pipe at one of its ends is held against and sealed at its inner and outer end surfaces to a filling head and at its other end is held by a back-up plate engaging the inner one of the tubes, so that the space between the tubes is in communication with atmosphere. Foamed grout is initially introduced to the annular space, forming a reservoir, by gravity so as not to destroy its foamed character and then is forced under relatively low pressure through the annular space lengthwise of the pipe. Gate valve means are provided at the entrance end to initiate and terminate the flow of grout and overflow receptacles are provided at each end of the pipe to collect surplus grout which falls out when the pipe is separated from the filling head and back up plate. This excess grout is then recirculated to the reservoir. After filling, the pipe is stored in racks for curing of the grout is then ready for shipment.

June 5, 1973 L. HACKER 3,737,493

FILLING AN ANNULAR SPACE BETWEEN RADIALLY SPACED COAXIAL TUBES WITHFOAMED CEMENT Filed March 1, 1971 2 Sheets-Sheet 1 lNVENTOR/S [EU/Ul/AC/EK BY Ja L914, 2;. M

ATTORNEYS L. HACKER June 5, 1973 FILLING AN ANNULAR SPACE BETWEENRADIALLY SPACED COAXIAL TUBES WITH FOAMED CEMENT 2 Sheets-Sheet 2 FiledMarch 1, 1971 INVENTOR/S AEOA/ A/AC/(EE BY d/fl(% .%adda, 12 41; an/manAT TO R N EYS United States Patent Olfice Patented June 5, 1973 US. Cl.264-42 5 Claims ABSTRACT OF THE DISCLOSURE A method and an apparatus aredisclosed for filling the annular space between radially spaced coaxialtubes constituting a double walled pipe. The pipe may be of extrudedplastic and comprises inner and outer coaxial tubes with bracing andspacing means therebetween. The pipe at one of its ends is held againstand sealed at its inner and outer end surfaces to a filling head and atits other end is held by a back-up plate engaging the inner one of thetubes, so that the space between the tubes is in communication withatmosphere. Foamed grout is initially introduced to the annular space,forming a reservoir, by gravity so as not to destroy its foamedcharacter and then is forced under relatively low pressure through theannular space lengthwise of the pipe. Gate valve means are provided atthe entrance end to initiate and terminate the flow of grout andoverflow receptacles are provided at each end of the pipe to collectsurplus grout which falls out when the pipe is separated from thefilling head and back-up plate. This excess grout is then recirculatedto the reservoir. After filling, the pipe is stored in racks for curingof the grout and is then ready for shipment.

BRIEF SUMMARY OF THE INVENTION The invention has to do with a method andan apparatus for filling the annular cylindrical space between inner andouter Walls constituting a pipe or conduit. A pipe or conduit which maybe filled by the method and the apparatus of the present invention isdisclosed and claimed in the Harry et al. patent, No. 3,379,221 grantedApr. 23, 1968. This patent discloses a conduit formed of concentrictubes of synthetic resinous material of specified flexural modulus,connected by spacing and bracing means which act in compression or intension, rather than in mere resistance to flexing, to secure theconcentric tubes against radial and angular displacement relative to oneanother. While the spacing and bracing means are capable of performingthese functions by themselves, it is highly advantageous that they beassisted in this function by a filler which substantially entirely fillsthe spaces between the webs. According to said patent, this filler is acementitious grout consisting of perlite, asbestos short fibers,portland cement, water, a resin, and sufficient air to produce a wetdensity of no more than about 50 pounds per cubic foot. Thiscementitious grout in accordance with said patent is pumped into thecells between the webs in the extruded product under pressure and thepipe is then allowed to cure for three to four days. According to thepresent invention, the annular space between the inner and outer tubesbe filled with a foamed grout which is then cured in situ'. In thefilling of the annular space, care must be exercised that the foamedcharacter of the grout is not destroyed.

Basically, the method involves permitting foamed grout to enter theannular space by gravity and then forcing the grout under relativelylight pressure through the annular space lengthwise of of the pipeagainst atmospheric pressure. When the annular space is filled, thegrout feed is stopped and excess grout is permitted to fall away intoreceptacles from which it is recirculated. The end of the pipe remotefrom the filling end has its annular space open to atmosphere so thatthe filling pressure need only overcome friction and atmosphericpressure.

From the apparatus standpoint, a reservoir is provided in communicationwith a filling head. The filling head is provided with a gate valve andwith an annular groove of dimensions to accept an end of the pipe to befilled. Means are provided to seal the filling head against the insideand outside of the pipe. The pipe is held against the filling head infilling position by means of a back-up plate so designed that it doesnot obstruct the annular space at that end of the pipe.

The pipe approaches the apparatus by rolling transversely of its lengthon rails and is then picked up by a walking beam arrangement anddeposited in supports. The back-up plate is then actuated to move thepipe axially into operative engagement with the filling head and thepipe is then sealed against the filling head. The gate valve is openedand the foamed grout begins to flow into the filling head and throughthe annular groove therein into the annular space between the two tubesconstituting the pipe. Then relatively light pressure is applied to thereservoir to force the foamed grout through the annular space lengthwiseof the pipe. When this space is completely filled, the gate valve in thefilling head is closed, the back-up plate is withdrawn and the pipe isaxially withdrawn from the filling head. Excess foamed grout from bothends of the pipe falls into receptacles from where it is recirculated tothe reservoir. Thereupon the walking beam mechanism lifts the pipe outof the pipe supports and deposits it upon inclined rails for movement tocuring racks or the like.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS FIG. 1 is anelevational view of the apparatus.

FIG. 2 is a more detailed view on an enlarged scale showing the fillinghead in vertical diametral cross section as viewed from the other sideof the apparatus.

DETAILED DESCRIPTION The apparatus as disclosed in FIG. 1 basicallycomprises a reservoir 10, a filling head 11, a back-up plate 12, pipesupports 13, a walking beam mechanism 14, rails 15 on which the pipe isfed to the apparatus and from which it passes on for subsequentprocessing, and the overflow receptacles 16, one beneath each end of thepipe in its filling position.

The reservoir 10 has a cover 17 which may be opened for inspection orcleaning and three ports are provided at 18, 19 and 20. Two of theseports are connected, respectively (connections not shown), to theoverflow receptacles 16 which are provided with pumping means 16a topump excess foamed slurry back to the reservoir '10 and the third one ofthe ports is connected to a source of foamed slurry.

The foamed slurry generally consists of portland cement and water and afoaming agent. This mixture with air under pressure is passed through amixing hose which is at least :fifty feet long so as to be thoroughlyhomogenized and then passes through one of the above mentioned portsinto the reservoir 10.

The filling head 11 is shown in more detail in FIG. 2 and it will beseen that it includes a gate valve element 21 actuated by means of afluid cylinder 22. The valve 21 is connected to the rod 23 of the pistonin the cylinder 22 by means of a clevis pin 24.

The filling head 11 per se has an annular passage 25 terminating in anannular groove 26 into which the end of the pipe to be filled isinserted. In order to seal the pipe to the filling head for a fillingoperation to prevent the grout from squirting outside the pipe, thegroove 26 is provided with inner and outer sealing means. These sealingmeans comprise an aluminum ring 27 and a U- shaped flexible element 28.On the outer periphery of the groove 26 there is a similar aluminum ring29 with a resilient member of U-shaped cross section 30. The U- shapedelements are disposed with their bases facing each other and ducts 31and 32 are provided, communicating with a source of air under pressurethrough a pipe 33.

From the foregoing description it will be understood that when an end ofthe double walled pipe is inserted into the groove 26 and pressure isapplied to the line 33, the elements 28 and 30 will be expanded towardeach other into engagement respectively with the inside of the inner oneof the tubes and with the outside of the outer one ofthe tubes so as toseal them against the filling head 11.

It will be understood that the inner member 34 of the filling head isheld to the outer portion of the filling head 35 by means of equallyspaced spider elements, one of which is hollow, to constitute thepassage 32. The plates 36 are hinged to the frame of the apparatus sothat when the clevis pin 24 is removed, the filling head and gate valvemay be swung out for cleaning or for replacement by a like filling headof a different diameter for use with pipe of a different diameter.

The pipe presently being filled by the instant apparatus ranged betweeneight inches and fifteen inches in diameter. Below eight inches, othertypes of pipe are more economical and likewise above about fifteeninches other types of pipe are more economical. Within the abovementioned range, however, pipe of a type herein discussed is currentlybeing used in sewer service and has been found to be very economical andefficient.

At the end of the pipe remote from the filling end there is provided theback-up plate 12 which, as clearly shown in FIG. 1, is beveled as at 37so that it does not obstruct the annular space between the two tubes.The back-up plate 12 is actuated by the piston of a fluid cylinder 38and piston rod 39.

The rails 15 at a small inclination permit the pipe to roll from aprevious operation to the apparatus of the present invention. A walkingbeam mechanism is generally indicated at 14 but is conventional and willnot be described in detail. It simply lifts the pipe off the rails 15and deposits it in the pipe support cradles 13. Means (not shown) areprovided to move the cradle 13 laterally to move the pipe P intoengagement with the filling head and to move it back out of engagementwith the filling head. The back-up plate 12 serves to hold the pipe inposition.

The sequence of operations is as follows. The pipe P rolls along therails 15 and is lifted by the walking beam meachanism 14 from the rails15 into the pipe supports on cradles 13. The back-up plate 12 advancesand the supports 13 also move toward the left of FIG. 1 to advance thepipe end into the filler head 11. The back-up plate remains in thisposition during the filling operation. Fluid pressure is applied to theline 33 to seal the pipe end against the filler head. The gate valve 21is then opened and initially the foamed grout flows by gravity into thefilling head and into the annular space. After the gate valve is fullyopen light pressure is applied to the reservoir by conventional means(not shown) to force the foamed grout longitudinally through the annularspace. When the annular space is completely filled, pressure on thereservoir 10 is released so that excess foamed grout can be releasedback to the reservoir so as to relieve internal pressure in the annularspace. The gate valve is then closed and the back-up plate 12 and thepipe supports 13 retract, thus removing the pipe from the filling head11. Of course pressure is also released from the line 33 to permit thepipe to be retracted from the groove 26. At this time any excess foamedgrout from the two ends of the pipe falls into the receptacle 16 fromWhere it is pumped back to the reservoir 10. The walking beam mechanism14 then lifts the filled pipe from the supports 13 and deposits it backon the rails 15 where it rolls on for storage and curing in a rack orother suitable arrangement. At this point, the walking beam mechanism isready to accept another section of pipe.

It will be understood that this sequence of operations is a timedsequence and is controlled by conventional means not forming a part ofthe invention and not shown.

The basically important feature of the method and the apparatus hereindisclosed and claimed is that it permits filling the annular space witha foamed grout without destroying the foamed character thereof as wouldbe the case if the grout were subjected to pressure. Thus, it must benoted that when pressure is applied to the reservoir 10, it is forcingthe grout throught the annular space against atmospheric pressure onlyand thus the pressure need only be high enough to overcome the frictionof the material through the annular space and atmospheric pressure.Thus, a pressure on the order of 0.1 MN./m. is sufficient.

It will be understood that modifications may be made without departingfrom the spirit of the invention and that therefore no limitation notspecifically set forth is to be implied or is intended.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as fol-.

lows:

1. In the method of filling the annular cylindrical spaces in a conduitformed of concentric tubes of synthetic resinous material connected byintegral spacing and bracing means, comprising pumping a foamed concreteinto said spaces under pressure until said spaces are substantiallycompletely filled; the improvement comprising selecting as the mixturefor the foamed concrete, a mixture consisting of water, portland cementand a foaming agent, and initially feeding said foamed concrete to saidspace, from one end of said conduit, by gravity, with said conduit in anapproximately horizontal position, then forcing said concrete under apressure only high enough to overcome the friction of the materialthrough the annular space, and atmospheric pressure, through said spacelengthwise of the pipe, and when said space is filled, removing saidpressure and permitting excess foamed concrete to fall away, whereby topreserve the foamed character of said concrete, and curing said foamedconcrete in situ.

2. The method of claim 1, wherein said concrete forcing pressure is ofthe order of 0.1 MN./m.

3. The method of claim 1, including the step of collecting the foamedgrout which falls away from both ends of the pipe, and recirculating itto the initial feed.

4. In the method of filling the annular cylindrical spaces in a conduitformed of concentric tubes of synthetic resinous material connected byintegral spacing and bracing means, comprising pumping a foamed concreteinto said spaces under pressure until said spaces are substantiallycompletely filled; the improvement comprising providing an apparatushaving a filling head, a back-up member, a reservoir for foamed concreteconnected to said filling head, and means to support said pipe in anapproximately horizontal position between said filling head and back-upmember, positioning and supporting said pipe in a substantiallyhorizontal position in sealing engagement with said filling head whilebacking the pipe with said back-up member without obstructing saidannular space, opening said filling head to permit said foamed concreteto start to flow into said space by gravity, thenplacing said reservoirunder a pressure only high enough to overcome the friction of thematerial through the annular space, and atmospheric pressure, to forcesaid concrete through said space lengthwise of the pipe, removing saidpressure and closing said filling head, removing said pipe from saidfilling head and back-up plate to permit excess foamed concrete to fallaway, whereby to preserve the foamed character of said concrete, andthen curing said concrete in situ.

5 5. The method of claim 4, wherein said concrete forcing pressure is ofthe order of 0.1 MN./m.'*.

References Cited UNITED STATES PATENTS 3,427,393 2/1969 Masterson 174231,774,292 8/1930 Reed ..17423 6 2,915,802 12/1959 Dugas 264-42 2,535,80812/1950 Mucher 264-262 X 3,379,221 4/1968 Harry et a1. 52-615 JOHN H.MILLER, Primary Examiner US. Cl. X.R.

